INERTIAL DEPOSITION OF PARTICLES IN THE HUMAN UPPER AIRWAY BIFURCATIONS

Particle deposition in symmetric bifurcating airways due to inertial i mpaction was studied numerically for inspiratory flows. Three-dimensio nal bifurcation models were constructed. The models had different pare nt and daughter diameters comparable to the airway generations 3-6 of the human lung. Bifurcation angles of the models were also varied (30 degrees, 45 degrees, and 60 degrees). Airflow fields in the models wer e obtained by a finite-element method (FIDAP, Fluid Dynamics Internati onal, Evanston, IL) for different Reynolds numbers of 100, 265, 530, a nd 1060 under parabolic and uniform inlet velocity conditions. The cal culated flow field data were used to simulate particle trajectory in t he airways. Particle deposition efficiency was obtained using the limi ting trajectory method. Inlet flow velocity profile, flow Reynolds num ber, and bifurcation angle were found to have substantial effects on p article deposition. Based on calculated deposition results, empirical equations were derived for particle deposition efficiency as a functio n of nondimensional parameters of Stokes number, Reynolds number, and bifurcation angle for a parabolic or a uniform inflow. The proposed fo rmulae compared favorably with available experimental data and are app licable to a particle lung deposition model. (C) 1997 American Associa tion for Aerosol Research.